Introduction of a temporary stiffness into knitted cotton for stability during patterning

ABSTRACT

Knitted cotton fabrics for durable-press textile products are given a temporary stability and stiffness by spray application of a stabilizing or firming agent after application of the durablepress finishing agent. The added stability and stiffness allow the fabric to be cut more easily into patterns for the textile product, but, because they are temporary, do not affect adversely the stiffness or feel of the final product.

United States Patent Frick et al.

INTRODUCTION OF A TEMPORARY STIFFNESS INTO KNITTED COTTON FOR STABILITYDURING PATTERNING lnventors: John G. Frick; Bethlehem K.

Andrews, both of New Orleans; Gloria A. Gautreaux, Metairie. all of La.

The United States of America as represented by the Secretary ofAgriculture, Washington, DC.

Filed: Apr. 17, 1973 Appl. No.: 351,935

Assignee:

US. Cl. 8/ll5.6; 138/144; 112/262; 117/4; 28/77 Int. Cl D07m 13/12 Fieldof Search 117/4; 8/1 15.6; 138/144; 112/262 51 Apr. 22, 1975 [56]References Cited UNITED STATES PATENTS 2.974.432 3/1961 Wamock et a1.38/144 3.036.537 5/1962 Breicr 28/77 UX 3.329.116 7/1967 Attwood et a1.28/77 UX Primary E.\'aminerDona1d Levy Attorney, Agent, or FirmM. HowardSilverstein; Max D. Hensley [57] ABSTRACT 3 Claims, No DrawingsINTRODUCTION OF A TEMPORARY STIFFNESS INTO KNITTED COTTON FOR STABILITYDURING PATTERNING FIELD TO WHICH THIS INVENTION RELATES This inventionrelates to a method for making knitted cotton fabric intended forpost-cured durable-press textile items easier to cut or otherwise shapeinto patterned parts of the final item without adversely affecting thefinal properties of the fabric. Specifically. this invention provides amethod of making the knitted cotton firm and stable enough to allow easypatterning or tailoring which method does not greatly increase thestiffness of the final durable-press product after it has been washed.

Definitions:

By the stability of a fabric we mean the resistance the fabric offers toundesired deformations. A stable knitted fabric can be handled and cutwithout changing the number of stitches for unit length in anydirection. This stability is related to the firmness of the fabric andis accompanied by a stiffness or rigidity.

A stabilizing or firming agent is a material that can be applied to afabric and give the stability or firmness described in the precedingparagraph.

Durable press refers to the ability of a fabric to resist wrinkling inwear and laundering. This property is obtained to a noticeable andimportant extent on cotton by finishing or treating with a crosslinkingagent.

Post-cure durable press refers to durable-press finishing of cottontextiles in which a crosslinking agent is applied to a length of fabric,but curing to promote reaction of the agent with the cotton is postponedor deferred until the fabric has been fashioned into the final textileitem.

Spray application means the deposition of a material on fabric bydispersing the material as fine particles and carrying these particlesto the fabric in a stream of gas. The particles are small enough totravel easily in a stream of gas moving through the atmosphere but arenot small enough to remain suspended indefinitely in an ordinaryatmosphere without a propelling stream of gas.

The Problem Knitted cotton fabric often lacks body and firmness and,therefore, lacks a stability in handling. As a consequence, it isdifficult to avoid accidental stretching, skewing, or other distortionin cutting or otherwise shaping the fabric to fit a pattern for part ofa textile article. The parts then are misshapen or missized, and thefinal shape of the article is distorted. This problem can be avoided bythe application of agents that give a stability and a stiffness to thefabric. Unfortunately, the properties introduced by these stabilizingagents when they are applied in the usual wet application are sometimespersistent. They remain through tailoring or other fabrication into thefinal textile product. This is often objectionable because it detractsfrom the softness and suppleness usually desired in articles of knittedfabric. The persistence of these properties is a particularly seriousproblem in durable-press articles treated by a post-cure process. Insuch treatments, the durable-press finishing agents are applied beforethe fabric is cut to patterns, but the fabric is not cured until thefinal textile article is formed. The stiffening agent is present,therefore, when the durable-press finishing agent is cured or set on thefabric. The stiffening agent tends to be bound by the finishing agent asa consequence. This tendency to bind the stiffening agent is aggravatedby the fact that many of the stiffening agents can react chemically withthe durable-press finishing agent.

The problem of misshaped fabric is also more serious in durable-pressitems because the shape and dimensions of the fabric cannot be changedby stretching or pressing after the durable-press treatment.

THE PRIOR ART No method of solving the problem is known in the priorart. Where it arises the problem is tolerated. The best compromise isusually employed where the stability of the fabric is less than idealand some stiffness. less than would be obtained with a fully stabilizedfabric. is allowed to persist in the final product. Otherwise. the useof knitted cotton is avoided.

OBJECT OF THE INVENTION The object of the instant invention is to applya stabilizing or firming agent to knitted cotton fabric being treatedfor post-cure durable-press textile items in such a manner that thefabric is stable enough to allow easy shaping to patterns but the fabricdoes not retain objectionable stiffness after the fabric is completelytreated and washed.

How the Objective is Achieved The objective of this invention isachieved by spraying a temporary stabilizing or firming agent on aknitted cotton fabric to which a durable-press finishing agent has beenapplied but which fabric has not been cured. Curing is then performedafter spray application of the stabilizing agent to promote reaction ofthe finishing agent.

The stabilizing or firmingagent can be any polymeric material that willadhere to the fabric and that has a modulus high enough to hold theyarns in place. These agents are commonly sold under the name of sizesor sizing agents. Spraying consists of blowing a fine dispersion ofsolution or dispersion of stabilizing agent onto the fabric. The solventor dispersing medium may be water or organic liquid. If the medium is aliquid of low volatility it must not be in such quantity that itsaturates any part of the fabric and causes movement of thedurable-press finishing agent as it flows on the fabric. With highlyvolatile liquids the problem is minimized because only a small quantityof liquid reaches the fabric.

After spraying the fabric with the firming agent of this invention thefabric is stable and firm enough for easy handling and shaping withoutcausing stretch or other distortion. After the fabric is cut and sewninto a garment or other textile item, it is cured by heating to impartdurable-press properties, that is, wrinkle resistance and the ability todry smooth. When the item is washed after curing, the stabilizing agentis removed. The fabric then has a stiffness no more than slightlygreater than a similar durable-press fabric that has not been treatedwith a stabilizing agent before curing for ease of shaping and cutting.

The ability to remove readily the stabilizing and stiffening agent inlaundering comes from the nature of the application. The stabilizingagent is only on the surface of the fabric and is not subject to bindingby the durable-press finishing agent, either through physical entrapmentor chemical attachment, when that agent reacts on curing. Withapplication by spraying, even those stabilizing agents that are capableof reacting with the durable-press finishing agent may be used. Forinstance, a starch product may be applied to the fabric containing thedurable-press finishing agent, and the fabric can be washed free ofnoticeable starch after curing.

SUMMARY OF THE lNVENTlON The instant invention can be described as amethod for providing knitted cotton fabric that is stable and firmenough to be cut easily into patterns without distortion, that can becured by heat to introduce durablepress properties, and that can berestored to near its original soft hand by washing after it has beencured.

1n the practice of this invention, a formulation commonly used in thedurable-press finishing of cottoncontaining fabric is applied to theknitted cotton fabric. This formulation contains 315% of a durable-pressfinishing agent that is a water-soluble crosslinking agent forcellulose. The preferred type of crosslinking agent for the process ofthis invention is a methylol amide, such as dimethyloldihydroxyethyleneurea, dimethylol ethyleneurea, dimethylolpropyleneurea, and dimethylol methyl carbamate. In addition, theformulation will contain a catalyst to promote reaction of thecrosslinking agent. Common catalysts are zinc nitrate, zinc'chloride,and magnesium chloride. Both agent and catalyst are dissolved in water.The aqueous formulation also may contain other substances such as handmodifiers for the fabric, wetting agent, or odor control agent.

The knitted cotton fabric is impregnated with the formulation bypadding. The wet, impregnated fabric is dried at 50-l00C until thefabric contains less than of fabric weight in residual water but is notheated long enough to cause extensive crosslinking by the durable-pressfinishing agent. Crosslinking at this stage of the process would make itdifficult to shape from the fabric garments or other textile items thatrequire sharp folds or creases.

After it is dried, the fabric is sprayed with the stabilizing agent.This is most conveniently a modified starch or other sizing materialdispersed in volatile liquid and under pressure. On release of pressureat a nozzle, a spray is formed, and the liquid rapidly evaporates. Thespray should be applied long enough to give the fabric a 1 to 3%increase in weight, distributed as uniformly as possible across thesurface. The fabric is then firm, stable, and moderately stiff. It canbe handled and smoothed easily when it is being prepared for cutting andwhile it is being cut to a pattern, without excessive stretching orother distortion of shape. After the patterned pieces are cut and sewnto form the desired garment or other textile item, the fabric is curedin its final form by heating 2-20 minutes at l40-180C. When the textileitem is washed following this treatment, the sprayed-on stabilzing andstiffening agent is removed. The fabric is then nearly as soft, pliable,and unwrinkled as a similar durable-press fabric that was treatedwithout using the stabilizing agent.

Note: With some sprays the fabric is dry after spraying without furtherattention. The solvent or dispersing media is volatile enough toevaporate during the operation. With a dilute water dispersion, morethan one drying step may be necessary.

The detailed description and specific examples that follow are providedmerely to illustrate the invention as well as preferred embodiments.These illustrations should not be construed as limiting the scope of theinstant invention in any manner whatever. Numerous changes andmodifications within the spirit of the invention will become apparent tothose skilled in the art. 1n the examples. components of the finishingformulations are listed with quantities designated as percentage of theweight of the total formulation. Weight gains of fabric samples arenoted as percentage of the weight of the original,- untreated fabric.Physical properties of the fabric samples were determined by testmethods described by the American Association of Textile Chemists andColorists and in Federal Test Methods. An increase in stiffness orbending moment, determined by the Tinius Olsen method, is taken as anindication of increased stability and firmness as well as a loss insoftness.

EXAMPLE 1 Samples of a cotton jersey were padded with a durable-pressformulation composed of 6% dimethylol dihydroxyethyleneurea, 1.8%magnesium chloride hexahydrate, and 0.5% polyethylene in water. Thesamples were dried by heating them in a mechanical convection oven at Cfor 10 minutes. Some samples of the fabric then were sprayed with anon-starch fabric sizing, sold commercially as Niagara Fabric Finish andSizing, by means of pressure from a volatile propellant to give 1.0-1.5%additional weight add-on to the fabric. Some samples, with and withoutthe sizing were cured by heating at C for 3 minutes. The samples leftuncured were used to demonstrate the properties of the fabric at thisstage of the treatment. This stage is the one where the fabric will becut to patterned pieces for making durable-press textile items. Curedsamples were washed by the usual home laundry procedure. The stiffnessand hand of the fabric samples are indicated by the bending moment inthe following table.

The data show that the sizing imparted stiffness at the stage of thetreatment where the textile item would be fabricated in a post-curedurable'press finishing procedure. Also, it is shown that aftercompletion of the treatment and washing the stiffness of the fabricapproached that in fabric treated without sizing. Actual feel of thefabric confirmed the test results.

Durable-press rating was unaffected by the temporary sizing; both fabricsamples that were cured and washed had a durable-press rating of 3.7.

EXAMPLE 2 A sample of cotton jersey was padded with an aqueousdurable-press formulation containing 6% dimethyloldihydroxyethyleneurea, 1.8% magnesium chloride hexahydrate, and 0.5%emulsified polyethylene. The fabric sample was dried at 70C for minutesand then sprayed with a modified starch dispersed in a volatile liquidunder pressure sold commercially as Easy-on Speed Starch. An add-on ofl.32.3% modified starch was obtained. At this stage of the treatment thefabric had bending moments of 7.2 X 10" and 5.5 X 10" in lb in lengthand width directions respectively. The fabric was then cured at 160C for3 minutes. After washing, the fabric dried smoothly and had bendingmoments of 2.0 X 10' and 1.8 X 10' in lb in length and width directions.Bending moments of the untreated fabric were 1.8 X 10 in lb in eachdirection.

EXAMPLE 3 Samples of a cotton jersey were padded with a durable-pressformulation composed of 6% dimethylol dihydroxyethyleneurea, 1.8%magnesium chloride hexahydrate, and 0.5% emulsified polyethylene inwater. The padded samples of fabric were dried at 70C for 10 minutes.Two samples of the padded and dried fabric were sprayed with a 10%aqueous solution of hydroxyethylated starch to give 1.0-l.5% weight gainafter drying. The spray was formed by an atomizer with compressed air.Two samples, one with the hydroxyethylated starch sizing and one withoutwere cured by heating at 160C for 3 minutes. The cured samples were thenwashed by a laundry procedure commonly used in the home. The procedureused a home-type laundry machine and a tumble dryer. Stiffness of thefabric samples are shown in the following table.

Bending moment, in lb X l0 Fabric sample lengthwise widthwise lllillDurable-press treated fabric with hydroxyethylated starch before curingafter curing and washing The fabric sprayed with the hydroxyethylatedstarch shows an increased stiffness or firmness before curing the pointin the process at which durable-press textile items are made from thefabric. After curing and washing, little of this increased stiffnesspersists. Durable-press ratings on both cured fabrics were between 3.5and 4.0 indicating that smooth-drying ability was about equal in bothsamples.

We claim:

1. A method of imparting temporary firmness and stability toknittedcellulosic fabrics intended for postcured durable-press goods,said temporary firmness and stability facilitating the cutting andshaping or forming of patterned knitted fabric during the stage ofprocessing between initial impregnation and the curing step, said curingstep occurring post-fabrication, without affecting the desired degree offinal stiffness, the method comprising impregnating the cellulosicknitted fabric with an aqueous solution containing a crosslinking agentand its catalyst, drying the wet impregnated fabric, spraying atemporary sizing solution to a dryweight pickup of about from I to 3%without saturating said fabric, submitting the treated knittedcellulosic fabric to fabrication, and curing the fabricated material.

2. A method of imparting temporary firmness and stability to knittedcellulosic fabrics intended for postcured durable-press goods in orderto facilitate the cutting and shaping or forming of patterned knittedfabric during the stage of processing, specifically between initialimpregnation and curing, wherein the curing step is postponed topost-fabrication, the method not affecting the desired degree of finalstiffness of the knitted fabric, the method comprising:

a. impregnating a cellulosic knitted fabric to a wet pickup of about 50to with a methylol amide crosslinking agent and catalyst,

b. drying the wet impregnated knitted fabric,

c. spraying a temporary sizing solution selected from the groupconsisting of modified starch, hydroxyethyl starch, and non-starchsizing without saturating said fabric,

d. submitting the impregnated knitted fabric to fabrication, and

e. curing the impregnated and fabricated goods.

3. A method of imparting temporary firmness and stability to knittedcellulosic fabrics intended for postcured durable-press goods in orderto facilitate the cut ting and shaping or forming of patterned knittedfabric during the stage of processing, specifically between initialimpregnation and curing, wherein the curing step is postponed topost-fabrication, the method without affecting the desired degree offinal stiffness, the method comprising:

a. impregnating a cellulosic knitted fabric to a wet pickup of about 50to 100% with an aqueous solution containing a methylol amidecrosslinking agent selected from the group consisting of dimethyloldihydroxyethyleneurea, dimethylol ethyleneurea, dimethylolpropyleneurea, and dimethylol methyl carbamate, and a catalyst selectedfrom the group consisting of zinc nitrate, zinc chloride, and magnesiumchloride,

b. drying the wet impregnated knitted cellulosic fabric for about from 2to 15 minutes at about from 60 to 100C,

c. spraying a temporary sizing solution selected from the groupconsisting of modified starch, hydroxyethyl starch, and non-starchsizing to a dry weight pickup of about from 1 to 3% without saturatingsaid fabric,

d. submitting the dry impregnated knitted cellulosic fabric to cutting,shaping, molding, or other fabrication desired, and

e. curing the fabricated goods for about from 2 to 20 minutes at aboutfrom to C, and washing the temporary sizing off and drying thecrosslinked goods.

1. A method of imparting temporary firmness and stability to knittedcellulosic fabrics intended for post-cured durable-press goods, saidtemporary firmness and stability facilitating the cutting and shaping orforming of patterned knitted fabric during the stage of processingbetween initial impregnation and the curing step, said curing stepoccurring post-fabrication, without affecting the desired degree offinal stiffness, the method comprising impregnating the cellulosicknitted fabric with an aqueous solution containing a crosslinking agentand its catalyst, drying the wet impregnated fabric, spraying atemporary sizing solution to a dry-weight pickup of about from 1 to 3%without saturating said fabric, submitting the treated knittedcellulosic fabric to fabrication, and curing the fabricated material. 1.A METHOD OF IMPARTING TEMPORARY FIRMNESS AND STABILITY TO KNITTEDCELLULOSIC FIBRICS INTENDED FOR POST-CURED DURABLEPRESS GOODS, SAIDPEMPORARY FIRMNESS AND STABILITY FACILITATING THE CUTTING AND SHAPING ORFORMING OF PATTERNED KNITTED FABRIC DURING THE STAGE OF PROCESSINGBETWEEN INITIAL IMPREGNATION AND THE CURING STEP, SAID CURING STEPOCCURRING POSTFABRICATION,WITHOUT AFFECTING THE DESIRED DEGREE OF FINALSTIFFNESS, THE METHOD COMPRISING INPREGNATING THE CELLULOSIC KNITTEDFABRIC WITH AN AQUEOUS SOLUTION CONTAINING A CROSSLINKING AGENT AND ITSCATALYST, DRYING THE WET IMPREGNATED FABRIC, SPRAYING A TEMPORARY SIZINGSOLUTION TO A DRY-WEIGHT PICKUP OF ABOUT FROM 1 TO 3% WITHOUT SATURATINGSAID FABRIC, SUBMITTING THE TREATED KNITTED CELLULOSIC FABRIC TOFABRICATION, AND CURING THE FABRICATED MATERIAL.
 2. A method ofimparting temporary firmness and stability to knitted cellulosic fabricsintended for post-cured durable-press goods in order to facilitate thecutting and shaping or forming of patterned knitted fabric during thestage of processing, specifically between initial impregnation andcuring, wherein the curing step is postponed to post-fabrication, themethod not affecting the desired degree of final stiffness of theknitted fabric, the method comprising: a. impregnating a cellulosicknitted fabric to a wet pickup of about 50 to 100% with a methylol amidecrosslinking agent and catalyst, b. drying the wet impregnated knittedfabric, c. spraying a temporary sizing solution selected from the groupconsisting of modified starch, hydroxyethyl starch, and non-starchsizing without saturating said fabric, d. submitting the impregnatedknitted fabric to fabrication, and e. curing the impregnated andfabricated goods.